1. Field of the Invention
This invention relates to improvements in a torque sensor for use in an electrically driven type power steering apparatus carried on a vehicle or the like for aiding in the steering operation and mitigating a force necessary for steering.
2. Related Background Art
A known electrically operated type power steering apparatus in a vehicle or the like is designed such that the rotational output of an electric motor, which provides an auxiliary steering torque, is decelerated by a gear device and is transmitted to the output shaft of a steering mechanism to thereby aid a steering force applied to a steering wheel and effect the steering of wheels. In such an electrically operated type power steering apparatus, a torque sensor is provided for detecting a steering force, i.e., a torque, transmitted to an input shaft. An electric motor is driven in conformity with the result of the detection by the torque sensor, whereby an auxiliary steering force is generated.
Such a torque sensor is described, for example, in Japanese Utility Model Application Laid-Open No. 1-142831 or 4-47638. In the torque sensor disclosed in these publications, a lead wire connected to a detection circuit portion and a coil winding wound on a bobbin are soldered together at a predetermined location on the coil winding. Also, flange portions at the opposite ends of the bobbin have of the same diameter.
This prior art, however, has suffered from the following problems. Firstly, there has been the possibility of the winding wound on the bobbin being damaged during the soldering of the winding and the lead wire and by the soldered portion itself and the coil winding being short-circuited or broken. In such case, the reliability of the sensor is not obtained.
Further, there has been the problem that if a great change in the shape is done in the direction of movement of a slider, the characteristic of the output of the sensor will vary, and also there has been the requirement that dimensions in the axial direction must be made small in terms of column layout.
Further, there has been the problem that if the shape is changed significantly in the direction of movement of a slider, the characteristic of the output of the sensor will be changed. Also, there has been the requirement that dimensions in the axial direction must be made small in terms of column layout.
Also, if assembly is done with the directions of two coils mistaken, the coils will be liable to be affected by a disturbance magnetic field to thereby reduce the performance. Therefore, special care is needed during assembling to ensure that the directions of the coils are correct.